Nickel and manganese‐doped CdS quantum dots: Optical study and photocatalytic activity on methylene blue

Abstract

Photo degradation of organic dyes by pure and doped CdS quantum dots (QDs) prepared by wet chemical route using mercaptoethanol as capping agent has been investigated. Synthesized QDs have been characterized by X‐ray diffraction (XRD) pattern, scanning electron microscopy (SEM), UV–visible, and photoluminescence (PL) spectrophotometry. Structural study confirmed the existence of the cubic phase, quasi spherical shape and well distribution with grain size of 10–20 nm. Optical studies show a blue shift in the absorbance spectrum with increasing the doping concentration. The PL spectra of Mn‐doped CdS show an additional orange‐red emission band at ∼645 nm, which is attributed from 4T1 (G) → 6A1(S) radiative transitions. Green luminescence band at ∼530 nm on Ni2+ doping can be arising to 1T2g → 3A2g transition. Photo catalytic activity of doped CdS QDs was studied on methylene blue (MB) dye. Methylene blue (MB) decomposition rate of pure and doped CdS QDs evaluated on methylene blue (MB) dye is as follows: CdS:Ni2+>CdS:Mn2+>CdS. A maximum photo degradation efficiency of MB dye (∼83%) was obtained by Ni2+‐doped CdS QDs. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 1194–1200, 2014